Histidine

Using amino-acid histidine as chelating agent, CdS nanoparticles have been synthesized by sonochemical method. It is found that by varying the ultrasonic irradiation time, we can tune the band gap and particle size of CdS nanoparticles. The imidazole ring of histidine captures the Cd ions from the solution, and prevents the growth of the CdS nanoparticles. The deviation in the linear relation in between cube of radius of nanoparticles and ultrasonic irradiation time confirms the growth of CdS nanoparticles occur via two process; one is the diffusion process of the reactants as well as reaction at the surface of the crystallite. CdS nanoparticles synthesized using histidine as organic chelating agent have band edge emission at ∼481 nm and have greater photoluminescence intensity with blue-shift to higher energy due to typical quantum confinement effect.

Immobilized Metal-Affinity Chromatography (IMAC) represents a relatively new separation technique that is primarily appropriate for the purification of proteins with natural surface-exposed histidine residues and for recombinant proteins with engineered histidine tags or histidine clusters. Because the method has gained broad popularity in recent years, the main recent developments in the field of new sorbents, techniques and possible applications are discussed in this article. Advantages of the method and new prospects are described as well as the problems and concerns that appear when the method is to be used for production of pharmaceutical-grade proteins.

This paper presents the results of our calculations on the geometric parameters, vibrational spectra and hyperpolarizability of a nonlinear optical material l-histidine oxalate. Due to the lack of sufficiently precise information on geometric structure in literature, theoretical calculations were preceded by re-determination of the crystal X-ray structure. Single crystal of l-histidine oxalate has been growing by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in the non-Centro symmetric space group P212121 of orthorhombic system. The FT-IR and Raman spectra of l-histidine oxalate were recorded and analyzed. The vibrational wave numbers were examined theoretical with the aid of Gaussian98 package of programs using the DFT//B3LYP/6-31G(d) level of theory. The data obtained from vibrational wave number calculations are used to assign vibrational bands obtained in IR and Raman spectroscopy of the studied compound. The geometrical parameters of the title compound are in agreement with the values of similar structures. To investigate microscopic second order non-linear optical NLO behaviour of the examined complex, the electric dipole μtot, the polarizability αtot and the hyperpolarizability βtot were computed using DFT//B3LYP/6-31G(d) method. According to our calculation, the title compound exhibits non-zero βtot value revealing microscopic second order NLO behaviour.. In acid-base hybrid crystals, hydrogen bonds play an important role not only in the creation of crystal structure and its stability, but also in the enhancement of the polarizability α and the hyperpolarizability β of the crystal due to the perturbation of the electronic structure of l-histidine and also due to the strong electron–phonon coupling.► In this study, l-histidine oxalate crystallizes in the space group P212121 of orthorhombic system. ► All the experimental vibrational bands have been discussed and assigned to normal mode. ► The non linear optical properties of l-histidine oxalate have been investigated by DFT method. ► The results indicate hydrogen bonding increased the hyperpolarizability of the crystal.

Background Affinity chromatography is one of the most efficient protein purification strategies. This technique comprises a one-step procedure with a purification level in the order of several thousand-fold, adaptable for various proteins, differentiated in their size, shape, charge, and other properties. The aim of this work was to verify the possibility of applying affinity chromatography in bacteriophage purification, with the perspective of therapeutic purposes. T4 is a large, icosahedral phage that may serve as an efficient display platform for foreign peptides or proteins. Here we propose a new method of T4 phage purification by affinity chromatography after its modification with affinity tags (GST and Histag) by in vivo phage display. As any permanent introduction of extraneous DNA into a phage genome is strongly unfavourable for medical purposes, integration of foreign motifs with the phage genome was not applied. The phage was propagated in bacteria expressing fusions of the phage protein Hoc with affinity tags from bacterial plasmids, independently from the phage expression system. Results Elution profiles of phages modified with the specific affinity motifs (compared to non-specific phages) document their binding to the affinity resins and effective elution with standard competitive agents. Non-specific binding was also observed, but was 102-105 times weaker than the specific one. GST-modified bacteriophages were also effectively released from glutathione Sepharose by proteolytic cleavage. The possibility of proteolytic release was designed at the stage of expression vector construction. Decrease in LPS content in phage preparations was dependent on the washing intensity; intensive washing resulted in preparations of 11-40 EU/ml. Conclusions Affinity tags can be successfully incorporated into the T4 phage capsid by the in vivo phage display technique and they strongly elevate bacteriophage affinity to a specific resin. Affinity chromatography can be considered as a new phage purification method, appropriate for further investigations and development.

Determination of protein–protein interactions is an important component in assigning function and discerning the biological relevance of proteins within a broader cellular context. In vitro protein–protein interaction methodologies, including affinity chromatography, coimmunoprecipitation, and newer approaches such as protein chip arrays, hold much promise in the detection of protein interactions, particularly in well-characterized organisms with sequenced genomes. However, each of these approaches attracts certain background proteins that can thwart detection and identification of true interactors. In addition, recombinant proteins expressed in Escherichia coli are also extensively used to assess protein–protein interactions, and background proteins in these isolates can thus contaminate interaction studies. Rigorous validation of a true interaction thus requires not only that an interaction be found by alternate techniques, but more importantly that researchers be aware of and control for matrix/support dependence. Here, we evaluate these methods for proteins interacting with DmsD (an E. coli redox enzyme maturation protein chaperone), in vitro, using E. coli subcellular fractions as prey sources. We compare and contrast the various in vitro interaction methods to identify some of the background proteins and protein profiles that are inherent to each of the methods in an E. coli system.

The purpose of this study was to evaluate the use of 3-methylhistidine (3MH) as an index of muscle protein degradation in dairy goats. The criterion for validation was the rapid and quantitative excretion of radiolabeled 3MH. Three adult dry does and four bucks were confined to metabolism cages and injected with 5 ml of L-3-[14C]methylhistidine dihydrochloride (4 microCi/mL) diluted in normal saline. The does' urine was collected from catheters and the bucks' urine from stainless steel separators protected with fecal collection bags. The daily urine samples were analyzed for labeled amino acid. Urinary recovery of radioactivity from all does was less than 33% after 3 d and was proceeding at less than 5% d. After 9 d, total recovery was less than 50% of total dose for the does. Elimination rates were slightly higher and more variable for the yearling bucks (25-63% after 4 d). On the basis of these data, 3MH does not appear to be a valid index of muscle protein degradation in ...

A replacement of both Cys residues by His in oxytocin (OXT) sequence allows for the formation of the stable complex with the {NH(2), N(Im), N(Im(macrochelate))} binding mode at the physiological pH. The detailed potentiometric and spectroscopic studies on the Cu(II) complexes of [His(1,6)]OXT, together with high resolution NMR investigations on 3D structures of Cu(II) complexes with [His(1,6)]OXT and [His(1,6)]AVP analogues are presented and discussed. Exchange of the Cys-S-S-Cys bridge by the His-Cu(II)-His motif is very promising, because the resulting complexes retain topological similarity to the native S-S bridged AVP and OXT at pH values corresponding to the physiological pH.

A new vasopressin analogue, [His1,6]AVP, was synthesized and characterized by potentiometric measurements as well as by UV-Vis, CD and EPR spectroscopy. At the physiological pH the peptide forms a stable complex with Cu2+ ions which is characterized by the {NH2, NIm, NIm(macrochelate)} binding mode. The replacement of both Cys by His residues in the vasopressin sequence results in a very significant increase in the efficiency of Cu2+ binding.